During fabrication of semiconductor devices on a wafer, chemical mechanical planarization (CMP) is performed to smooth surfaces of the wafer using chemicals and/or mechanical forces. For example, the wafer can be polished to prepare the wafer for a new layer of material. In one example of polishing, the wafer can be secured to a polishing head configured to hold and rotate the wafer (e.g., vacuum pressure can be used to secure the wafer to the polishing head). The polishing head can apply force to the wafer toward a polishing pad during polishing. The polishing head can rotate the wafer against the polishing pad, which can also be rotating, to apply mechanical force to the wafer to remove material and/or even out irregular topography of the wafer, for example. In one example, chemicals, such as slurry (e.g., colloid), can be applied to the polishing pad during polishing to serve as solvents which aid in reducing non-uniformities on the surface of the wafer.